U.S. Pat. No. 4,696,229, BEZLER et al, assigned to the assignee of the present application and the disclosure of which is hereby incorporated by reference, discloses a structure which, generally, permits printing selectively by respective printing couples. For printing with blanket cylinders engaged against each other, with the substrate web therebetween, the impression cylinder which is not needed at that time is used as a paper guide roller. The paper guide roller is located downstream, in the path of the moving web, with respect to one of the printing couples. It may occur that, upon the first printed web contacting the impression cylinder, ink which has just been applied may smear on the substrate.